This disclosure relates to thermoplastic compositions, specifically copolymer compositions comprising a combination of ester units, carbonate units, and siloxane units, methods of manufacture of such copolymers, and articles and uses thereof.
Thermoplastic compositions comprising polycarbonates are known for their impact strength, transparency, and melt-flow characteristics, and are used in the manufacture of articles and components for a wide range of applications, from automotive parts, to packaging materials, to electronic appliances. The properties of thermoplastic polycarbonate polymers may be further adjusted by the inclusion of discrete, compositionally different polymer units. Condensation copolymers comprising polyesters and polycarbonates, and particularly those compositions additionally comprising polysiloxanes, exhibit advantageous non-Newtonian melt viscosity behavior and better low temperature ductility and thick section impact than corresponding non-polysiloxane-containing polyester polycarbonates.
However, copolymer combinations containing aromatic ester units, carbonate units, and siloxane units have been found to exhibit phase separation, as evidenced by low transparency and high degrees of haze. These optical characteristics can limit the utility and potential applications of such copolymers. There accordingly remains a need for copolymers containing aromatic ester units, carbonate units, and siloxane units wherein the melt flow and/or ductility properties of the combination is achieved while maintaining high transparency and low haze.
Terpolymers containing these functional units may be prepared by solution phase polymerization. However, the de novo preparation of such terpolymers by solution phase polymerization may be expensive to justify for a developing market, and may not benefit sufficiently from economies of scale to be profitable. It is desirable therefore to prepare thermoplastic compositions that perform equivalently and that may be prepared by more readily scaled processes from bulk feedstock, without the isolation and workup expenses of a basic synthetic approach. In particular, it would be desirable to develop methods for the manufacture of copolymers comprising aromatic ester, carbonate, and siloxane units that do not rely on solution phase polymerization.